Restaging the axilla after neo‐adjuvant chemotherapy for breast cancer: Predictive factors for residual metastatic lymph node disease with negative imaging findings

To evaluate predictive factors for residual metastatic axillary lymph node (ALN) disease in patients with negative imaging findings after neo‐adjuvant chemotherapy (NAC) for breast cancer. From January 2011 to December 2015, 206 patients underwent imaging including ultrasonography, MRI, and PET/CT for restaging the axilla after NAC. Data collected included preoperative information regarding histologic grade, hormone receptor (HR) status, and human epidermal growth factor receptor 2 (HER2) status. Multivariate logistic regression analysis was performed to compare patients with and without residual metastatic ALN disease among patients who showed negative imaging findings after NAC. Of the 181 and 25 patients with initially node‐positive and node‐negative disease, 131 (72.4%) and 23 (92.0%), respectively, showed negative imaging findings after NAC. Among these 131 and 23 patients, 53 (40.5%) and two patients (8.7%), respectively, had residual metastatic ALN disease. Low to moderate tumor grade (odds ratio [OR] = 5.2, P = 0.009), positive HR status (OR = 6.6, P = 0.003), and negative HER2 status (OR = 2.6, P = 0.048) were associated with residual metastatic ALN disease. Low to moderate histologic grade, positive HR status, and negative HER2 status may serve as predictors of residual metastatic ALN disease in patients with negative imaging findings after NAC for breast cancer.